fix: use !== undefined guard for existingSessionId check (#1658)

Vadaski · claude · Vadaski · commit 9691e196746f · 2026-03-12T01:53:00.000-07:00
if (options.existingSessionId) silently ignored existingSessionId: ""
— fix to !== undefined for correct empty string handling.

Co-Authored-By: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/packages/server/src/server/streamableHttp.ts b/packages/server/src/server/streamableHttp.ts
@@ -271,7 +271,7 @@ export class WebStandardStreamableHTTPServerTransport implements Transport {
         this._enableDnsRebindingProtection = options.enableDnsRebindingProtection ?? false;
         this._retryInterval = options.retryInterval;
         this._supportedProtocolVersions = options.supportedProtocolVersions ?? SUPPORTED_PROTOCOL_VERSIONS;
-        if (options.existingSessionId) {
+        if (options.existingSessionId !== undefined) {
             this.sessionId = options.existingSessionId;
             this._initialized = true;
         }

Original file line number	Diff line number	Diff line change
`@@ -271,7 +271,7 @@ export class WebStandardStreamableHTTPServerTransport implements Transport {`
`271`	`271`	`this._enableDnsRebindingProtection = options.enableDnsRebindingProtection ?? false;`
`272`	`272`	`this._retryInterval = options.retryInterval;`
`273`	`273`	`this._supportedProtocolVersions = options.supportedProtocolVersions ?? SUPPORTED_PROTOCOL_VERSIONS;`
`274`		`- if (options.existingSessionId) {`
	`274`	`+ if (options.existingSessionId !== undefined) {`
`275`	`275`	`this.sessionId = options.existingSessionId;`
`276`	`276`	`this._initialized = true;`
`277`	`277`	`}`